Variable valve lift follower for vehicle

ABSTRACT

A variable valve lift follower for a vehicle includes an outer body receiving a rotational force from a high lift cam; an inner body with a first end portion hinge-connected with the outer body, receiving a rotational force from a low lift cam; a hydraulic lash adjuster (HLA) contact portion for supplying oil to the first end portion of the inner body; a valve contact portion on a second end of the inner body; and a knock pin on the top of the valve contact portion, connecting the outer body to the inner body during high lift.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Korean Patent Application No.10-2006-0098272, filed on Oct. 10, 2006, the entire disclosure of whichis hereby incorporated by reference.

BACKGOUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a variable valve lift follower for avehicle and, more particularly, to a variable valve lift follower for avehicle having a knock pin in a valve contact portion.

2. Description of Related Art

In general, since the rotational speed of internal combustion enginesvaries from about 500 rpm to 6,000 rpm, the flow of air taken in theengine varies considerably. In a reciprocating internal combustionengine that controls the flow quantities of the air and exhaust gas byopening and closing intake valves and exhaust valves, to obtain highpower when driving at high speed, it is necessary to increase the chargeefficiency by prolonging the time that the intake valves are open whichmakes the overlap with the exhaust valves larger and thereby therotational state of the engine becomes bad when driving at low speed.Accordingly, it is necessary to keep the overlap within a predeterminedrange.

Variable valve lift systems have been used to improve the outputperformance of the engine by adjusting the opening and closing timingsof the intake valves and the exhaust valves with various operatingconditions of the engine.

A valve contact portion is established on the bottom of one side of theinner body of the variable valve lift follower and a hydraulic lashadjuster (HLA) contact portion is provided on the other side.

A lock plate body and a lock plate connected with each other are mountedon one end of an inner body.

One end portion of the lock plate body is connected with the lock plateand the other end portion of the lock plate body comes in contact withthe piston.

Since the lock system, such as lock plate and the like, is positioned onthe HLA side, the other parts of the variable valve lift areconcentrated in the valve contact portion. Accordingly, the effectivemass of the follower adds an inertia mass to the valves' motion, thusinfluencing the dynamic behavior of the valve train.

The above information disclosed in this Background section is only forenhancement of understanding of the background of the invention andtherefore it may contain information that does not form the prior artthat is already known in this country to a person of ordinary skill inthe art.

SUMMARY OF THE INVENTION

The present invention provides a variable valve lift follower for avehicle, comprising: an outer body receiving a rotational force from ahigh lift cam; an inner body, one end portion of which ishinge-connected with the outer body, receiving a rotational force from alow lift cam; a hydraulic lash adjuster (HLA) contact portion to supplyoil to the end portion of the inner body; a valve contact portion on theother end of the inner body; and a knock pin, installed on the top ofthe valve contact portion, connecting the outer body with the inner bodyduring high lift.

In an exemplary embodiment, the variable valve lift follower furthercomprises an oil path connecting the HLA contact portion with the knockpin to transmit oil pressure from the HLA contact portion to the knockpin.

In a further exemplary embodiment, the oil path includes a firstconnection path connected with the HLA contact portion, a secondconnection path formed in the horizontal direction with the firstconnection path, and a third connection path that transmits the oilpressure from the second connection path to the knock pin, the first andthird connection path being inclined.

An oil supply hole may further be provided on an end of the secondconnection path and a cap may be attached detachably on the oil supplyhole.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view depicting a variable valve lift systemaccording to an embodiment of the present invention;

FIG. 2 is a perspective view illustrating a variable valve lift followerin accordance with an embodiment of the present invention;

FIG. 3 is a perspective view illustrating an inner body in accordancewith an embodiment of the present invention; and

FIG. 4 is a bottom view of FIG. 3.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Hereinafter, preferred embodiments of the present invention will bedescribed in detail with reference to the attached drawings.

In some embodiments, a variable valve lift follower includes three camsfor each valve to control the opening amounts of the valve based onengine conditions by the rotational force of a cam assembly. A middlelow lift cam 10 and two high lift cams 11 are disposed in a row.

A knock pin, formed on the top of the valve contact portion 51positioned opposite to the HLA 23, moves in the longitudinal directionto connect an inner body 54 and an outer body 55 with each other, thusapplying a high lift thereto.

An HLA contact portion 50 supplying oil to the inner body 54 is providedon the bottom of one side of the inner body 54, a valve contact portion51 is provided on the bottom of the other side of the inner body 54, andthe knock pin is installed on the top of the valve contact portion 51.

The knock pin is installed on the other end of the inner body 54 so asto move in the forward and backward directions (based on thelongitudinal direction of the outer body) by the oil pressure, and ahinge pin 56 is disposed on one end of the inner body 54, through whichthe outer body 55 and the end portion of the inner body 54 arehinge-connected with each other, thus allowing the other end portion ofthe outer body 55 to rotate independently.

Since the knock pin is moved by the oil pressure, the oil path 52 isprovided to connect the HLA contact portion 50 with a cylinder 53including the knock pin, thus supplying oil introduced through the HLAcontact portion 50 to the knock pin.

The oil path 52 comprises a first connection path 52 a connected withthe HLA contact portion 50, a second connection path 52 b formed in thehorizontal direction and fluidly connected to the first connection path52 a, and a third connection path 52 c coupling the second connectionpath 52 b to the cylinder 53.

The first and third connection paths 52 a and 52 c are inclined. Thepaths 52 a and 52 c can be inclined at various angles to avoidinterference with peripheral parts. An oil supply hole 57 extending tothe outside is disposed on an end of the second connection path 52 b anda cap is attached detachably onto the oil supply hole 57.

Operation of the variable valve lift follower in accordance with anembodiment of the present invention will now be described.

(1) When applying high lift: the oil is introduced to the inner body 54through the HLA contact portion 50 in the period of high speed of fullload, supplied from the HLA contact portion 50 to the first connectionpath 52 a of the oil path, and moved to the second and third connectionpath 52 b and 52 c, thus transmitting the oil pressure to the knock pinin the cylinder 53.

Subsequently, the knock pin is pushed out from the inner body 54 by theoil pressure and the rotational forces of the high lift cams 11 aretransmitted to the knock pin when the other end portion rotatesdownward, thus becoming in a high lift state.

(2) When applying low lift: as the oil charged in the cylinder isexhausted in the period of low speed of part load, the knock pin isreturned to the inside of the inner body 54 and, as the oil moves fromthe oil path 52 to the HLA contact portion 50 and is discharged to theHLA 23, the outer body 55 and the inner body 54 are separated from eachother to rotate independently. The valve is operated only by the innerbody 54, thus becoming in a low lift state.

The present invention can reduce stress and friction caught by the valvespring to enhance the fuel efficiency and the engine performance byproviding a knock pin connecting the outer body 55 with the inner body54 on the top of the valve contact portion. The oil path 52, throughwhich the oil is received from the HLA 23 transmits the oil pressure tothe knock pin.

As described above, according the variable valve lift follower inaccordance with the present invention, it is possible to reduce theeffective mass of the valves and decrease the stress and friction on thevalve spring, thus enhancing the fuel efficiency and the engineperformance, by providing the knock pin connecting the outer body withthe inner body on the top of the valve contact portion and by formingthe oil path, through which the oil is received from the HLA and the oilpressure is transmitted to the knock pin.

While this invention has been described in connection with what ispresently considered to be practical exemplary embodiments, it is to beunderstood that the invention is not limited to the disclosedembodiments, but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

1. A variable valve lift follower for a vehicle, comprising: an outerbody configured to receive a rotational force from a high lift cam; aninner body comprising a first end portion hinge-connected with the outerbody, configured to receive a rotational force from a low lift cam; ahydraulic lash adjuster (HLA) contact portion configured to supply oilto the first end portion of the inner body; a valve contact portiondisposed on a second end of the inner body; and a knock pin, disposed ona top of the valve contact portion, configured to connect the outer bodyto the inner body during a high lift.
 2. The variable valve liftfollower as recited in claim 1, further comprising an oil path fluidlyconnecting the HLA contact portion with the knock pin.
 3. The variablevalve lift follower as recited in claim 2, wherein the oil pathcomprises a first connection path connected to the HLA contact portion,a second connection path connected to the first connection path, and athird connection path connecting the second connection path to the knockpin, wherein the first and third connection paths are inclined and thesecond connection path is substantially horizontal.
 4. The variablevalve lift follower as recited in claim 3, further comprising an oilsupply hole on an end of the second connection path, and a cap attacheddetachably onto the oil supply hole.